def prettyPrintMatrix(matrix):
	s = [[str(e) if not e is None else " - " for e in row] for row in matrix]
	lens = [max(map(len, col)) for col in zip(*s)]
	fmt = '\t'.join('{{:{}}}'.format(x) for x in lens)
	table = [fmt.format(*row) for row in s]
	print('\n'.join(table))